Fluoro-Jade® B staining as useful tool to identify activated microglia and astrocytes in a mouse transgenic model of Alzheimer's disease

Fluoro-Jade® B is known as a high affinity fluorescent marker for the localization of neuronal degeneration during acute neuronal distress. However, one study suggested that fluoro-Jade® B stains reactive astroglia in the primate cerebral cortex. In this study, we analyzed the staining of fluoro-Jade® B alone or combined with specific markers for detection of glial fibrillary acidic protein (GFAP) or activated CD68 microglia in the double APPSL/PS1 KI transgenic mice of Alzheimer's disease (AD), which display a massive neuronal loss in the CA1 region of the hippocampus. Our results showed that fluoro-Jade® B did not stain normal and degenerating neurons in this double mouse transgenic model. Fluoro-Jade® B was co-localized with Aβ in the core of amyloid deposits and in glia-like cells expressing Aβ. Furthermore, fluoro-Jade® B was co-localized with CD68/macrosialin, a specific marker of activated microglia, and with GFAP for astrocytes in APPSL/PS1 KI transgenic mice of AD. Taken together, these findings showed that fluoro-Jade® B can be used to label activated microglia and astrocytes which are abundant in the brain of these AD transgenic mice. It could stain degenerating neurons as a result of acute insult while it could label activated microglia and astrocytes during a chronic neuronal degenerative process such as AD for example.